Organo-Photocatalytic Anti-Markovnikov Hydroamidation of Alkenes with Sulfonyl Azides: A Combined Experimental and Computational Study

Rui Fu¹, Mengyu Xu¹, Yujing Wang¹, Xinxin Wu^2,*, Xiaoguang Bao^{1,3,*（鲍晓光）}

¹ Soochow Univ, Coll Chem Chem Engn & Mat Sci, Innovat Ctr Chem Sci, 199 Ren-Ai Rd,Suzhou Ind Pk, Suzhou 215123, Jiangsu, Peoples R China

² Soochow Univ, Coll Chem Chem Engn & Mat Sci, Key Lab Organ Synth Jiangsu Prov, Suzhou 215123, Jiangsu, Peoples R China

³ Soochow Univ, Jiangsu Key Lab Adv Negat Carbon Technol, Suzhou 215123, Jiangsu, Peoples R China

Angew. Chem. Int. Ed. 2024, 63, e202406069

The construction of C(sp³)-N bonds via direct N-centered radical addition with olefins under benign conditions is a desirable but challenging strategy. Herein, we describe an organo-photocatalytic approach to achieve anti-Markovnikov alkene hydroamidation with sulfonyl azides in a highly efficient manner under transition-metal-free and mild conditions. A broad range of substrates, including both activated and unactivated alkenes, are suitable for this protocol, providing a convenient and practical method to construct sulfonylamide derivatives. A synergistic experimental and computational mechanistic study suggests that the additive, Hantzsch ester (HE), might undergo a triplet-triplet energy transfer manner to achieve photosensitization by the organo-photocatalyst under visible light irradiation. Next, the resulted triplet excited state ³HE* could lead to a homolytic cleavage of C⁴-H bond, which triggers a straightforward H-atom transfer (HAT) style in converting sulfonyl azide to the corresponding key amidyl radical. Subsequently, the addition of the amidyl radical to alkene followed by HAT from p-toluenethiol could proceed to afford the desired anti-Markovnikov hydroamidation product. It is worth noting that mechanistic pathway bifurcation could be possible for this reaction. A feasible radical chain propagation mechanistic pathway is also proposed to rationalize the high efficiency of this reaction.

链接：https://onlinelibrary.wiley.com/doi/10.1002/anie.202406069